Dino card No. 1314 of 2,027

Ophthalmosaurus

Say it: of-THAL-moh-SORE-us

Name means: “eye lizard”1

Ate: MeatIchthyosaursEarly Jurassic to Early CretaceousNot technically a dinosaur

Ophthalmosaurus was a sleek, fast-swimming marine reptile with enormous eyes, almost as big as dinner plates. It lived in the warm seas of the Jurassic period and hunted small fish and squid. Even though it looked like a dolphin, it was actually an ichthyosaur, not a dinosaur.1

Fun fact: this sea reptile swam while dinosaurs walked on land. Everyone calls them dinos, but they were a different branch of reptiles.

Lived

201 to 133 million years ago2

Early Jurassic to Early Cretaceous

Fossils found in

Fossils found in the United Kingdom, Argentina, the United States, Russia, France, and Greenland, including the Oxford Clay in England and the Sundance Formation in the USA.2 1

Food

Meat1

Length

4 m1

Weight

930 kg to 950 kg1

When did it live?

Triassic

Jurassic

Cretaceous

252 million years ago20114566, the asteroid

How big was it?

as long as 2 bicycles in a rowas long as 22 bananas end to endas heavy as 32 big dogsas heavy as 190 watermelons

How big was Ophthalmosaurus compared to YOU?

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cool stuff

Fun facts

Ophthalmosaurus had eyes that measured about 22 to 23 centimetres (8.7 to 9.1 inches) across, which is bigger than a human head.1

It could dive to depths of 600 metres (2,000 feet) or more, reaching the twilight zone of the ocean, and stay underwater for about 20 minutes.1

Its tail ended in a two-lobed fin, with the lower half supported by the backbone and the upper half made only of soft tissue, helping it swim fast.1

Ophthalmosaurus had short, rounded limbs, with the front ones bigger than the back ones, which it used for steering rather than paddling.1

Fossils show it lived in shallow seas, like the Oxford Clay in England, which was only about 50 metres (160 feet) deep at the time.1

Some scientists think Ophthalmosaurus could swim at about 2 metres per second (6.6 feet per second) when chasing prey.1

AI-made picture of Ophthalmosaurus — An AI-made picture of how Ophthalmosaurus might have looked, made by a computer from what scientists know. It is a guess: the real animal may have looked different, and nobody knows its true colours.

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Myth buster

Myth: Ophthalmosaurus was a dinosaur that lived in the water.

Truth: Ophthalmosaurus was an ichthyosaur, a marine reptile, not a dinosaur. Ichthyosaurs were a different group of reptiles that lived in the oceans.1

For dino experts

Scientific name: Ophthalmosaurus
Named by: Seeley 18742
Group: Ichthyosaurs
Family / clade: Ophthalmosauridae2
Classification: Ichthyosauria > Ichthyosauromorpha2
Age of the rocks: 201 to 133 million years (Hettangian / Valanginian)2
Rock formations: Oxford Clay, Sundance, Vaca Muerta2
Countries: United Kingdom, Argentina, USA, Russia, France, Greenland2
Fossil records: 27 in the Paleobiology Database2
Also known as: Ancanamunia, Yasykovia (older names now counted as the same animal)2
Discovery: Ophthalmosaurus was first described by Harry Seeley in 1874, based on fossils from the Oxford Clay in England. He focused on the shape of the collarbone bones.1 2
Still debated: Scientists still debate whether some species, like Ophthalmosaurus natans from North America, are really separate species or just close relatives.1

Where the facts come from

Ophthalmosaurus (en.wikipedia.org)
Ophthalmosaurus in The Paleobiology Database (CC BY 4.0): age, places, rock formations, classification.

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